Web applications

This is a mini-rant, a short essay refuting a common misconception among users of an Internet forum.
If you think this essay is FUD, feel free to explain why on the essay's talk page.

Some people propose to circumvent the political restrictions on applications for mobile phones and consumer tablets, such as the rules of the iPhone Developer Program, by replacing them with web applications.
This just trades off political restrictions for technical restrictions.
A web application environment capable of replacing the native execution environment would require well-documented JavaScript APIs for every input device on the hardware, including multitouch and any built-in camera, accelerometer, and GPS.
It would also require a kickass JavaScript JIT engine, WebGL, and full support for HTML5 offline features (CACHE MANIFEST and localStorage).
As far as I know, current tablets aren't entirely there yet.

iPhone and iPad

The browser on the iPod touch, iPhone, and iPad is Mobile Safari.
As of January 2011, I haven't been able to find any evidence that Mobile Safari supports WebGL (tried Google mobile safari webgl).
I checked for how big a web app could be (tried Google mobile safari offline limit), and it appears to be limited to 5 MB. The localStorage object is likewise limited to 5 MB (tried Google mobile safari localstorage limit).
Nor does Mobile Safari appear to JIT compile the JavaScript due to iOS's especially strong flavor of W^X (tried Google mobile safari javascript jit).
Even accelerometer support wasn't added until iOS 4.2.